What to expect?

I’ve done that route a few times. I-25 north to US 18 east to WY 585 north to I-90 east to US 85 north to I-94 east.

 

The times I went I’d either stop at Big D in Belle Fourche or the Flying J just west of Bismarck.

 

Easy drive. I would highly recommend taking 585 just past Newcastle to take you to I-90 in Sundance and then going East to exit 10 in Spearfish, SD to catch back to 85. Otherwise you will be taking windy roads through the Black Hills and it will take longer. If it were me on that route I would stay the night at the Frontier truck stop in Bowman, ND and then go the rest of the way to Bismarck in the morning. Best wishes on your trip!

 

Great drive. I live SW of Bismarck on the Mandan side of the Missouri River. Drove that route dozens of times, and last week I did it for the first time with my kids in a minivan on a trip to NM and back. 25 out of Denver to US 85 just north of Cheyenne. Run that through Torrington, Lingle, Lusk, and north of Newcastle, take 585 to Sundance. Hop on 90 eastbound to catch 85 again at Spearfish, SD. Run 85 to Belfield, ND. 94 east to Bismarck. If you start fresh in Aurora, Bowman, ND has a decent little stop. Belle Fourche has a CBH Cenex there that I prefer. But plenty of places to stay.